In addition, since their adblocker isn't an extension and doesn't care about extension APIs, they can do things even Manifest v2 Chrome extensions can't. For example, full-fat uBO can't do CNAME uncloaking on Chromium due to API limitations, but can do it on Firefox which has the APIs. Brave is Chromium-based, but since Shields isn't an extension they've built CNAME uncloaking into it.